J. Shahbazi Karami - University of Shahid Rajaee Teacher Training, Iran
S. Sepahi-Boroujeni - University of Bu-Ali Sina, Iran.
Mohsen Khodsetan - School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran. *Corresponding author

Expansion equal channel angular extrusion (Exp-ECAE) is a severe plastic deformation (SPD) operation for processing bulk materials. In the current study, AA۷۰۷۵ Al was SPD-processed by expansion equal channel angular extrusion (Ex-ECAE) at various temperatures and ram velocities. Then, using split Hopkinson pressure bar (SHPB), the severely deformed products were compressed at room temperature and strain rates of ۰.۱~۳۰۰۰ s-۱. Both the strain rate sensitivity (SRS) and the apparent activation volume (AAV) were determined for all deformed samples. The results revealed that the Ex-ECAE operation has noticeably increased the SRS. The tensile strength at a strain rate of ۳۰۰۰ s-۱ was ۶ times increased by conducting Ex-ECAE at ۱۰۰ °C and with a ram velocity of ۷ mm/min. Ex-ECAE was also capable of considerably decreasing the AAV. The results showed the yield stress of both the Exp-ECAE and the annealed samples increased with increasing the strain rate. Also, the results showed that after the Exp-ECAE process, the AAV reached to ۶.۳ b۳ from the initial values of ۱۱۸.۵ b۳ in the annealed state.

AA۷۰۷۵ Aluminum Alloy, Dynamic Behavior, Expansion Equal Channel Angular Extrusion, Hopkinson Pressure Bar, Severe Plastic Deformation